Why does the queue switch elements around when I use the remove method? I am trying to implement a BFS algorithm. I$\text{'}$m using Java $17.$

allVertices.clear$()$;

vertex$1.$status $=$ "discovered";

Queue queue $=$ new PriorityQueue$<>()$;

queue.add$($vertex$1)$;

while $(!$queue.isEmpty$())\{$

System.out.print$("$Queue$"+$ queue$)$;

Vertex toRemove $=$ queue.remove$()$;

ArrayList oldNeighbors $=$ new ArrayList$($toRemove$.$neighbors$)$;

$//$ System.out.print$("$Queue added" $+$ queue$)$;

for $($int i $=0$; i $<$ oldNeighbors.size$()$; i$++)\{$

toRemove.disconnect$($oldNeighbors$.$get$($i$))$;

if $($oldNeighbors$.$get$($i$).$status.equals$("$undiscovered$"))\{$

oldNeighbors.get$($i$).$status $=$ "discovered";

queue.add$($oldNeighbors$.$get$($i$))$;

toRemove.connect$($oldNeighbors$.$get$($i$))$;

$\}$

$//$ System.out.println$("$neighbors:$"+$ toRemove.neighbors$)$;

$\}$

toRemove.status $=$ "explored";

allVertices.add$($toRemove$)$;

$\}//$ BFS algorithm

allVertices.clear$()$;

vertex$1.$status $=$ "discovered";

Queue queue $=$ new PriorityQueue$<>()$;

queue.add$($vertex$1)$;

while $(!$queue.isEmpty$())\{$

System.out.print$("$Queue$"+$ queue$)$;

Vertex toRemove $=$ queue.remove$()$;

ArrayList oldNeighbors $=$ new ArrayList$($toRemove$.$neighbors$)$;

$//$ System.out.print$("$Queue added" $+$ queue$)$;

for $($int i $=0$; i $<$ oldNeighbors.size$()$; i$++)\{$

toRemove.disconnect$($oldNeighbors$.$get$($i$))$;

if $($oldNeighbors$.$get$($i$).$status.equals$("$undiscovered$"))\{$

oldNeighbors.get$($i$).$status $=$ "discovered";

queue.add$($oldNeighbors$.$get$($i$))$;

toRemove.connect$($oldNeighbors$.$get$($i$))$;

$\}$

$//$ System.out.println$("$neighbors:$"+$ toRemove.neighbors$)$;

$\}$

toRemove.status $=$ "explored";

allVertices.add$($toRemove$)$;

$\}$